Touch mania swipes across markets

Touchscreens’ runaway market appeal has given rise to a mature worldwide supply chain in just a few years, encompassing the manufacturing plants in Taiwan and Japan where the transparent sensors are fabricated; the U.S. and European manufacturers of the controller chips that translate changes in resistance or capacitance into finger-down locations; and module makers and system integrators that add the clear cover, laminate the transparent films and integrate the electronics.

Legacy, resistive touchscreen technology uses two conductive polymers on separate layers that can be deformed to touch each other wherever a finger or stylus touches the top layer. Resistive controllers—which are available off the shelf from Analog Devices, Texas Instruments, STMicroelectronics and other mixed-signal chip makers—are relatively simple and very accurate, but they do not usually recognize multiple touches. Divergent architectures have been developed for resistive touchscreens, using varying numbers of connecting wires (such as four-wire or eight-wire) to make the task simpler or more accurate for specific applications.

“Touchscreen technology is extremely diverse, with many methods specialized for different applications; but in general resistive is the legacy technology, while projected capacitive has recently become the industry leader,” said Jenny Colegrove, vice president for emerging display technologies at DisplaySearch.

Projected capacitive touchscreens rule the roost in high-end mobile devices. Smart appliances and security keypads have no real need for capacitive touchscreens, however, and for some applications even resistive touchscreens are overkill. “Resistive touchscreens are still popular because of [the technology’s] maturity and low price point, whereas projected capacitive still has some issues with yields and the lamination process for large-scale screens,” said IHS iSuppli’s Alexander. “As long as you have a variety of screen sizes, application environments, price points and use cases for these devices, you are still going to need a variety of touchscreen technologies available.”

Projected capacitive technology drives one plate of a transparent capacitor with a signal, then measures the results at the adjacent plate with an analog-to-digital converter. The capacitive sensors are usually cast in a diamond pattern, with one diamond-shaped capacitor plate on each side of the glass or both on the same side, using whisker-sized jumpers. A smartphone uses a couple of hundred capacitive sensors and tablets up to 10 times as many, making it possible for a smart controller chip to discern any number of touches at resolutions fine enough to detect even the smallest child’s finger. Several controller makers, including Cypress and Integrated Device Technology (IDT), are proposing proprietary patterns that eliminate the need for jumpers.

Multitouch gesture capability began with two fingers to zoom, three to scroll and four to swipe; it’s now become a free-for-all, as multitouch variations proliferate to enable finer manipulation of on-screen objects. High-quality transparent sensor patterns support smart gesture recognition, but the smarts originate in controller algorithms that debounce and condition the signal from multiple fingers. The touchscreen controller sends the information to the application processor, which in turn identifies gestures of varying complexity, such as tap- to-select, brush-to-scroll and pinch-to-zoom.

Touchscreens are evolving toward allowing multiple finger touches to manipulate objects on-screen in much the same way objects might be handled on a real desktop.Click on image to enlarge.

@R_Colin_Johnson: thank you, good summary on the state-of-the-art of touch technology.
EE Times had a number of publications on the geopolitical ramifications of supply chain that source rare earth metals not too long ago. I think the optical touch technology seems to have good promise. I particularly like the technology developed by NextWindow cited in the article:
http://www.nextwindow.com/index.html
@David Ashton: NextWindow's technology will probably alleviate some of the difficulties users may face in touch-screen keyboards. Depending on the resolution in placement of the light sources and detectors, it will be possible to limit double- or wrong-entries of inputs.
MP Divakar

Perhaps voice will work for dictating letters and such, but never for writing code or similar when you need to say the names of symbols.
I've seen someone dictate a python program. It was painful. C would have been worse.

Yes and no... Apple certainly sold the world on using a touch screen with your fingers rather than with a stylis.
Apple could never have done this with old resistive touch though. The old resistive methods just can't produce the accuracy that Apple gets when you type on a touch screen.

I really don't think touch will every be popular for desktops.
Just try to simulate the experience. Reaching forward to touch a screen at a seated workstation is really slow and doing a lot would cause your arms to tire quickly.

It's not the lack of tactile feedback that gets me off balance on touch screens. For me, it's more a case of finger positioning. I seem to be happy if I can have some sort of audible key press feedback instead of a mechanical action. Mechanical is best, but, for me, audible works too.
However, I really struggle with specific finger positions. This is where the tactile feedback is needed for me. An overlay that's transparent and flat over the key area, but with small ridges around the outline for the key might just solve the problem for me. The touch keypad could have the ridges there permanently, but then some of the flexibility would be gone. You could customize character sets or key arrangement (Dvorak), but you couldn't change the size or number of keys.
Alternately, the ridges could be on a thin overlay as you sometimes see for computer game commands. That way, you could use it with or without the ridges and you'd have all of the flexibility as well as tactile information for positioning.

Those who complain that they need the tactile feel of keystrokes need to realize that the future is touch based. (And I agree further in the future, voice based)
Typing on a keyboard is loud and annoying. Typing on a touchscreen is silent. Ask my wife when I bring my laptop to bed.
Imagine the people who grew up with the first typewriters. The kind that physically hurl the inked letter to the paper. Did they complain when they switched from the manual to electromechanical versions? "I like to see my letters fly through space and land on my paper"

The responsiveness of a touch panel requires a lot of tuning. Apple has done a great job.
Touch screen didn't get popular until gestures recognition is "created". With it, user can do more. I agree that Touchscreen is good for mobile device. I don't think it can replace mouse and keyboard. However, the 3D gestures recognition like what Kinect is delivered may have a chance.

People think that technology decides winners, always. Not always. It is about perception. The cool thing about this is because of Apple. They made us imagined it and then the market came up. It is not just the technology.